Iran ? Iran announced Wednesday it now has 5,000 centrifuges operating and enriching uranium, the country’s latest defiance of U.N. demands to halt its controversial nuclear program.

Vice President Gholam Reza Aghazadeh said Iran will continue to install more centrifuges and enrich uranium to produce nuclear fuel for future Iranian nuclear power plants. In August, Iran said it had 4,000 centrifuges running at its plant in the central city of Natanz.

Uranium enriched to a low level is used to produce nuclear fuel, but further enrichment makes it suitable for use in nuclear weapons.

“At this point, more than 5,000 centrifuges are operating in Natanz and enriching uranium,” said Aghazadeh, who is head of the Atomic Energy Organization of Iran. He spoke to reporters during an exhibition of Iranian nuclear achievements at Tehran University.

Flaunting Iran’s defiance of international demands, Aghazadeh said the Islamic Republic will never suspend enrichment.

“Suspension has not been defined in our lexicon,” he said.